1. Field of the Invention
The invention relates to a filtration apparatus for filtering and regenerating a machining fluid, used for a machining process with a machine tool such as a milling machine, machining center, a grinding machine, or an electric discharge machine.
2. Description of the Related Art
In a machine tool, such as a milling machine, machining center, a grinding machine, or an electric discharge machine, machining fluid is directed to a machining region, between a workpiece to be machined and a tool, to remove heat and chips generated during the machining process. The machining fluid used for the machining process is filtered to separate the chips from the machining fluid. The machining fluid thus treated is recirculated to the machine tool. In the prior art, various filtration apparatuses have been used.
As a first prior art, Japanese Examined Patent Publication (Kokoku) No. 2-44564 describes a filtration apparatus which has a filter drum provided in a dirty tank for containing a machining fluid which has been used in a machining process. The filter drum includes a cylindrical filter and a hollow shaft defining an output port for passing the machining fluid into a clean tank. The machining fluid in the dirty tank flows from the outside to the inside of the cylindrical filter and the machining fluid is filtered to separate the particles suspended in the machining fluid. The dirty tank is provided with a plurality of scrapers for scraping a sediment of the particles separated from the machining fluid. The scrapers are moved by a pair of chains attached to the ends of the scrapers.
In the first prior art, the filter is cleaned by the machining fluid directed onto a portion of the filter which portion is in the air. Therefore, the chips in the form of adhesive sludge can not removed from the filter. Further, the filtration apparatus employs a filter drum which is relatively large. Therefore, the filtration apparatus becomes large and, in particular, it is essentially high and the replacement of the filter is difficult. Further, as described above, the machining fluid flows through the output port defined by the shaft of the drum filter. Therefore, provided around the bearing for supporting the shaft is a rotational sealing member, which is easily worn and continual replacement is required.
As a second prior art, Japanese Patent Publication No. 2512846 describes an apparatus for filtering a coolant for a machine tool. The apparatus includes a dirty tank and a clean tank fluidly connected to the dirty tank with a filter provided therebetween. The dirty tank is provided with a scraper conveyer. In order to wash filter, the filtered coolant in the clean tank is directed to the filter through a nozzle which is movable in the vertical direction.
In the second prior art, the scraper conveyer and the mechanism for moving the nozzle are driven by separate driving mechanisms. Therefore, the manufacturing cost is increased.
As a third prior art, Japanese Unexamined Patent Publication (Kokai) No. 9-300171 describes a filtration system which includes a hinge belt for separating relatively large chips in the form of curls or clusters from a machining fluid and for transporting the chips. However, the hinge belt can not remove relatively small particles. Therefore, the filtration system can further include a fine filter in the form of a rotating drum for separating relatively small chips in the form of sludge suspended in the machining fluid. However, a filtration system with a rotating filter drum has problems similar to those of the first prior art.
The invention is directed to solve the prior art problems, and to provide an improved filtration apparatus for filtering and regenerating a machining fluid. The filtration apparatus is relatively small, it is easy to replace the filter, and the apparatus can separate chips which are relatively small as well as large curling or clustered chips.
According to the invention, a filtration apparatus for filtering and regenerating a machining fluid, used for a machining process with a machine tool, the machining fluid containing particles generated during the machining process, is provided. The filtration apparatus includes a dirty tank for receiving the machining fluid; a clean tank fluidly connected to the dirty tank; filter means, provided between the dirty and the clean tanks, for filtering the machining fluid which flows from the dirty tank into the clean tank; conveyer means, provided in the dirty tank, for conveying a sediment of particles separated from the machining fluid in the dirty tank; collection means for receiving the particles from the conveyer means; and a filter cleaning for cleaning the filter means, the filter cleaning device including a nozzle bar, provided in the clean tank for rotation within a plane parallel to the filter means, for directing the machining fluid in the clean tank onto the filter means to blow the particles off the filter means into the dirty tank.
According to another feature of the invention, the filtration apparatus includes a dirty tank for receiving the machining fluid; a first clean tank fluidly connected to the dirty tank; a second clean tank fluidly connected to the first clean tank; first filter means, provided between the dirty and the clean tanks, for filtering the machining fluid which flows from the dirty tank into the first clean tank; second filter means, provided between the first and the second clean tanks, for filtering the machining fluid which flows from the first clean tank into the second clean tank; conveyer means, provided in the dirty tank, for conveying a sediment of particles separated from the machining fluid in the dirty tank; collection means for receiving the particles from the conveyer means; a first filter cleaning device for cleaning the first filter means, the first filter cleaning device including a nozzle bar, provided in the first clean tank for rotation within a plane parallel to the first filter means, for directing the machining fluid in the first clean tank to the first filter means to blow the particles off the first filter means into the dirty tank; and a second filter cleaning device for cleaning the second filter means, the second filter cleaning device including a nozzle bar, provided in the second clean tank for rotation within a plane parallel to the second filter means, for directing the machining fluid in the second clean tank to the second filter means to blow the particles off the second filter means into the first clean tank.